gnu-social/lib/activitystreams/activitycontext.php

<?php
/**
 * StatusNet, the distributed open-source microblogging tool
 *
 * An activity
 *
 * PHP version 5
 *
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  Feed
 * @package   StatusNet
 * @author    Evan Prodromou <evan@status.net>
 * @author    Zach Copley <zach@status.net>
 * @copyright 2010 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPLv3
 * @link      http://status.net/
 */

if (!defined('STATUSNET')) {
    exit(1);
}

class ActivityContext
{
    public $replyToID;
    public $replyToUrl;
    public $location;
    public $attention = array();    // 'uri' => 'type'
    public $conversation;
    public $conversation_url;
    public $scope;

    const THR     = 'http://purl.org/syndication/thread/1.0';
    const GEORSS  = 'http://www.georss.org/georss';
    const OSTATUS = 'http://ostatus.org/schema/1.0';

    const INREPLYTO  = 'in-reply-to';
    const REF        = 'ref';
    const HREF       = 'href';

    // OStatus element names with prefixes
    const OBJECTTYPE = 'ostatus:object-type';   // FIXME: Undocumented!
    const CONVERSATION = 'conversation';

    const POINT     = 'point';

    const MENTIONED    = 'mentioned';

    const ATTN_PUBLIC  = 'http://activityschema.org/collection/public';

    function __construct($element = null)
    {
        if (empty($element)) {
            return;
        }

        $replyToEl = ActivityUtils::child($element, self::INREPLYTO, self::THR);

        if (!empty($replyToEl)) {
            $this->replyToID  = $replyToEl->getAttribute(self::REF);
            $this->replyToUrl = $replyToEl->getAttribute(self::HREF);
        }

        $this->location = $this->getLocation($element);

        foreach ($element->getElementsByTagNameNS(self::OSTATUS, self::CONVERSATION) as $conv) {
            if ($conv->hasAttribute('ref')) {
                $this->conversation = $conv->getAttribute('ref');
                if ($conv->hasAttribute('href')) {
                    $this->conversation_url = $conv->getAttribute('href');
                }
            } else {
                $this->conversation = $conv->textContent;
            }
            if (!empty($this->conversation)) {
                break;
            }
        }
        if (empty($this->conversation)) {
            // fallback to the atom:link rel="ostatus:conversation" element
            $this->conversation = ActivityUtils::getLink($element, 'ostatus:'.self::CONVERSATION);
        }

        // Multiple attention links allowed

        $links = $element->getElementsByTagNameNS(ActivityUtils::ATOM, ActivityUtils::LINK);

        for ($i = 0; $i < $links->length; $i++) {
            $link = $links->item($i);

            $linkRel  = $link->getAttribute(ActivityUtils::REL);
            $linkHref = $link->getAttribute(self::HREF);
            if ($linkRel == self::MENTIONED && $linkHref !== '') {
                $this->attention[$linkHref] = $link->getAttribute(ActivityContext::OBJECTTYPE);
            }
        }
    }

    /**
     * Parse location given as a GeoRSS-simple point, if provided.
     * http://www.georss.org/simple
     *
     * @param feed item $entry
     * @return mixed Location or false
     */
    function getLocation($dom)
    {
        $points = $dom->getElementsByTagNameNS(self::GEORSS, self::POINT);

        for ($i = 0; $i < $points->length; $i++) {
            $point = $points->item($i)->textContent;
            return self::locationFromPoint($point);
        }

        return null;
    }

    // XXX: Move to ActivityUtils or Location?
    static function locationFromPoint($point)
    {
        $point = str_replace(',', ' ', $point); // per spec "treat commas as whitespace"
        $point = preg_replace('/\s+/', ' ', $point);
        $point = trim($point);
        $coords = explode(' ', $point);
        if (count($coords) == 2) {
            list($lat, $lon) = $coords;
            if (is_numeric($lat) && is_numeric($lon)) {
                common_log(LOG_INFO, "Looking up location for $lat $lon from georss point");
                return Location::fromLatLon($lat, $lon);
            }
        }
        common_log(LOG_ERR, "Ignoring bogus georss:point value $point");
        return null;
    }

    /**
     * Returns context (StatusNet stuff) as an array suitable for serializing
     * in JSON. Right now context stuff is an extension to Activity.
     *
     * @return array the context
     */

    function asArray()
    {
        $context = array();

        $context['inReplyTo']    = $this->getInReplyToArray();
        $context['conversation'] = $this->conversation;
        $context['conversation_url'] = $this->conversation_url;

        return array_filter($context);
    }

    /**
     * Returns an array of arrays representing Activity Objects (intended to be
     * serialized in JSON) that represent WHO the Activity is supposed to
     * be received by. This is not really specified but appears in an example
     * of the current spec as an extension. We might want to figure out a JSON
     * serialization for OStatus and use that to express mentions instead.
     *
     * XXX: People's ideas on how to do this are all over the place
     *
     * @return array the array of recipients
     */

    function getToArray()
    {
        $tos = array();

        foreach ($this->attention as $attnUrl => $attnType) {
            $to = array(
                'objectType' => $attnType,  // can be empty
                'id'         => $attnUrl,
            );
            $tos[] = $to;
        }

        return $tos;
    }

    /**
     * Return an array for the notices this notice is a reply to 
     * suitable for serializing as JSON note objects.
     *
     * @return array the array of notes
     */

     function getInReplyToArray()
     {
         if (empty($this->replyToID) && empty($this->replyToUrl)) {
             return null;
         }

         $replyToObj = array('objectType' => 'note');

         // XXX: Possibly shorten this to just the numeric ID?
         //      Currently, it's the full URI of the notice.
         if (!empty($this->replyToID)) {
             $replyToObj['id'] = $this->replyToID;
         }
         if (!empty($this->replyToUrl)) {
             $replyToObj['url'] = $this->replyToUrl;
         }

         return $replyToObj;
     }

}